Lind.DDD~实体属性变更追踪器的实现

回到目录

看着这个标题很复杂,大叔把它拆开说一下,实体属性-变更-追踪器,把它拆成三部分大家看起来就容易懂一些了,实体属性:领域实体里有自己的属性,属性有getter,setter块,用来返回和设置属性的内容;变更:当前属性为赋值时,我们对它进行监视;追踪器:对变量的内容进行处理。好了，我们回到Lind.DDD框架中，在框架里有领域实体基类EntityBase，这个类是所有实体的基类，它公开了一些属性和方法，我们对这个基类进行一些设置，让所有子类都继承它，享用它。

1 属性变更追踪接口和它的事件

    // 摘要:
    //     向客户端发出某一属性值已更改的通知。
    public interface INotifyPropertyChanged
    {
        // 摘要:
        //     在更改属性值时发生。
        event PropertyChangedEventHandler PropertyChanged;
    }

2 基类EntityBase,添加了事件和它的方法，及触发事件的方法

    /// <summary>
    /// 领域模型，实体模型基类，它可能有多种持久化方式，如DB,File,Redis,Mongodb,XML等
    /// Lind.DDD框架的领域模型与数据库实体合二为一
    /// </summary>
    [PropertyChangedAttribute]
    public abstract class EntityBase : ContextBoundObject, IEntity, INotifyPropertyChanged
    {
        /// <summary>
        /// 实体初始化
        /// </summary>
        public EntityBase()
        {
            this.Status = Status.Normal;
            this.UpdateDateTime = DateTime.Now;
            this.CreateDateTime = DateTime.Now;
            this.PropertyChanged += EntityBase_PropertyChanged;
        }

        /// <summary>
        /// 建立时间
        /// </summary>
        [XmlIgnore, DataMember(Order = ), XmlElement(Order = ), DisplayName("建立时间"), Column("CreateTime"), Required]
        public DateTime CreateDateTime { get; set; }
        /// <summary>
        /// 更新时间
        /// </summary>
        [XmlIgnore, DataMember(Order = ), XmlElement(Order = ), DisplayName("更新时间"), Column("UpdateTime"), Required]
        public DateTime UpdateDateTime { get; set; }
        /// <summary>
        /// 实体状态
        /// </summary>
        [XmlIgnore, DataMember(Order = ), XmlElement(Order = ), DisplayName("状态"), Required]
        public Status Status { get; set; }

        /// <summary>
        /// 拿到实体验证的结果列表
        /// 结果为null或者Enumerable.Count()==0表达验证成功
        /// </summary>
        /// <returns></returns>
        public IEnumerable<RuleViolation> GetRuleViolations()
        {
            var properties = this.GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance).ToArray();

            foreach (var i in properties)
            {
                var attr = i.GetCustomAttributes();
                foreach (var a in attr)
                {
                    var val = (a as ValidationAttribute);
                    if (val != null)
                        if (!val.IsValid(i.GetValue(this)))
                        {
                            yield return new RuleViolation(val.ErrorMessage, i.Name);
                        }
                }
            }

        }

        #region PropertyChangedEventHandler Events
        /// <summary>
        /// 属性值变更事件
        /// </summary>
        public event PropertyChangedEventHandler PropertyChanged;
        /// <summary>
        /// 事件实例
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void EntityBase_PropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            Console.WriteLine("属性:{0},值:{1}", e.PropertyName, sender.GetType().GetProperty(e.PropertyName).GetValue(sender));
        }
        /// <summary>
        /// 触发事件,写在每个属性的set块中CallerMemberName特性表示当前块的属性名
        /// </summary>
        /// <param name="propertyName"></param>
        public void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }

        #endregion

    }

3 定义变更拦截器特性

    /// <summary>
    /// 类中方法拦截的特性
    /// </summary>
    public class PropertyChangedAttribute : ProxyAttribute
    {
        public override MarshalByRefObject CreateInstance(Type serverType)
        {
            PropertyChangedProxy realProxy = new PropertyChangedProxy(serverType);
            return realProxy.GetTransparentProxy() as MarshalByRefObject;
        }
    }

4 实现拦截器功能

    /// <summary>
    /// 属性变更拦截器
    /// </summary>
    public class PropertyChangedProxy : RealProxy
    {
        Type serverType;
        public PropertyChangedProxy(Type serverType)
            : base(serverType)
        {
            this.serverType = serverType;
        }
        public override IMessage Invoke(IMessage msg)
        {
            //构造方法
            if (msg is IConstructionCallMessage)
            {
                IConstructionCallMessage constructCallMsg = msg as IConstructionCallMessage;
                IConstructionReturnMessage constructionReturnMessage = this.InitializeServerObject((IConstructionCallMessage)msg);
                RealProxy.SetStubData(this, constructionReturnMessage.ReturnValue);
                return constructionReturnMessage;
            }
            //其它方法（属性也是方法,它会被翻译成set_property,get_property,类似于java里的属性封装）
            else if (msg is IMethodCallMessage)
            {

                IMethodCallMessage callMsg = msg as IMethodCallMessage;
                object[] args = callMsg.Args;
                IMessage message;
                try
                {

                    if (callMsg.MethodName.StartsWith("set_") && args.Length == )
                    {
                        string propertyName = Regex.Split(callMsg.MethodName, "set_")[];
                        //这里检测到是set方法，然后应怎么调用对象的其它方法呢？
                        var method = this.serverType.GetMethod("OnPropertyChanged");
                        if (method != null)
                        {
                            var obj = GetUnwrappedServer();
                            obj.GetType().GetProperty(propertyName).SetValue(obj, args.FirstOrDefault());
                            method.Invoke(obj, new object[] { propertyName });//这块对象为空了
                        }

                    }

                    object o = callMsg.MethodBase.Invoke(GetUnwrappedServer(), args);
                    message = new ReturnMessage(o, args, args.Length, callMsg.LogicalCallContext, callMsg);
                }

                catch (Exception e)
                {

                    message = new ReturnMessage(e, callMsg);

                }

                return message;

            }

            return msg;

        }
    }

5 总结

本例子主要让大家了解了事件，事件触发机制，AOP拦截技术等知识点，而且通过本例子，我们可以对类的属性进行监视，并订阅一些方法来处理这些变更行为！下面这个代码是最简单的属性变更的记录，本user对象为赋值时，它的两个被set的属性成为了监视的对象

     User u1 = new User();
     u1.UserName = "OK";
     u1.Age = ;

aaarticlea/png;base64,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" alt="" />

回到目录